Field of the Inventions
The present disclosure relates to devices and methods for the percutaneous delivery and implantation of a cardiac valve prosthesis. The valve prosthesis can be delivered in a collapsed state within a sheath to the valve and released in situ.
Description of the Related Art
The mitral valve, also referred to as the left atrioventricular or bicuspid valve, has two primary leaflets, the anterior and posterior leaflets, and a subvalvular apparatus consisting of chordae tendineae attaching to the anterior and posterior papillary muscles of the left ventricle. A healthy mitral valve allows blood to flow unimpeded from the left atrium to the left ventricle during diastole and prevents regurgitation during systole. Normal mitral valve function depends not only on the integrity of the underlying valvular structure, but on the adjacent myocardium as well.
There are three types of mitral valve disease: mitral stenosis, mitral regurgitation and mitral valve prolapse. Mitral stenosis refers to the narrowing of the mitral valve orifice, thereby impairing the filling of the left ventricle in diastole. Mitral regurgitation is leakage of blood from the left ventricle backwards into the left atrium during systole. Mitral valve prolapse is the systolic billowing of one or both mitral leaflets into the left atrium during systole.
If the mitral valve becomes diseased or damaged, it may be surgically repaired to restore function. In many cases, however, the valve is too damaged to permit repair and the valve must be replaced with a prosthetic (artificial) valve. Currently open heart surgical repair and replacement of the mitral valve are the two main options to treat mitral regurgitation. Open chest mitral valve replacement has been used to treat patients with mitral valve regurgitation since the 1960s. The patient's diseased mitral valve is replaced by either a mechanical or a bioprosthetic valve. Open heart surgical procedure needs surgical opening of the thorax, the initiation of extra-corporeal circulation with a heart-lung machine, stopping and opening the heart, excision and replacement of the diseased valve, and restarting of the heart. While valve replacement surgery typically carries a 1-4% mortality risk in otherwise healthy persons, a significantly higher morbidity is associated to the procedure largely due to the necessity for extra-corporeal circulation. Further, open-heart surgery is often poorly tolerated in elderly patients.
Percutaneous approaches to mitral valve repair have been developed to reduce the clinical disadvantages of the open-heart procedures. In some percutaneous techniques, a prosthesis is advanced in a catheter through the patient's vasculature to the vicinity of the mitral valve. These transcatheter techniques include transfemoral delivery in which a device is implanted through the femoral artery and transapcial in which implantation is through a small incision in the chest and through the apex of the heart. These percutaneous techniques are attractive alternatives to conventional surgical treatment because they do not require open-heart surgery or extracorporeal circulation, and can be used in a closed and beating heart. The treatment is potentially less morbid and can be applied to a wider range of patients including those with less severe valvular dysfunction.
Transcatheter or percutaneous mitral valve replacement is particularly demanding technically, primarily due to the complex mitral valve and subvalvular anatomy, the absence well-structured implant site, the often multifactorial coinciding etiologies in mitral valve diseases, and the frequent occurrence of mitral valve annulus prolapse. Current techniques of transcatheter mitral valve repair still have a high percentage of procedural failures or complications. Their long-term efficiency is relatively low in particular because of a high rate of recurrent mitral regurgitation. Significant challenges therefore remain for transcatheter mitral valve replacement and consequently and despite a particularly invasive side, surgical repair is the treatment usually recommended for diseases of the mitral valve.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.